There is a continuing need for cooking and food warming fuel containers and burners which are able to produce an effective temperature level for an extended period of time. These cooking fuel containers and burners often use a fuel that is classified as non-flammable for a greater level of safety during usage and transportation. It is preferred that the cooking fuel container and burner produce a temperature in an oven, chafing dish or buffet server of at least about 160.degree. F., and preferably at least about 180.degree. F., throughout the majority of its full burn time. The burn time for a cooking fuel container and burner should be at least about three hours, and preferably at least about four hours. A cooking fuel container and burner which will produce a cooking temperature of at least about 180.degree. F. or greater and have a burn time of at least four hours will provide sufficient heat to chafing dishes and buffet servers for a sufficient period of time so that the cooking fuel containers do not have to be changed during a serving session.
The previous cooking fuel containers are able to provide a cooking temperature of about 180.degree.-190.degree. F. for about three hours. These devices are relatively efficient in burning and provide sufficient cooking temperature throughout a substantial portion of the life of the device. The burn temperature of these devices is fixed by the design of the burner. There are occasions when the user desires a higher temperature than that provided by the previous fuel containers.
It is known that the burn temperature of a fuel is dependent in part by the amount of air being fed to the flame. Numerous devices in the past have included air inlets to the fuel burn area to optimize combustion. Devices of this type typically include a fuel container for supporting a solid or liquid fuel and cover having a central opening for the flame to exit the container. One or more openings are also provided in the cover spaced outwardly from the central opening to feed air downwardly into the container. These air inlets generally feed air to a single burn front. Examples of this type of fuel burning device include U.S. Pat. No. 1,446,353 to Slocum; U.S. Pat. No. 1,919,622 to Sevcik; U.S. Pat. No. 1,226,625 to Ball; U.S. Pat. No. 1,267,475 to Stroble; British Pat. No. 168,871; British Pat. No. 388,335; German Pat. Publication No. 678,253; German Pat. Publication 2 618 394; and German Pat. Publication No. 2 804 589.
Another form of device for feeding air to a flame in a fuel container is disclosed in U.S. Pat. No.3,371,659 to Paspalas. This device includes a conventional fuel container having an open top. A removable cover having upstanding sidewalls extending from the wall of the container for supporting a cooking vessel. The wall of the cover includes a plurality of openings to allow air to enter the cover. U.S. Pat. No. 4,188,938 to Hasenfratz discloses a similar burner device having a plurality of air inlet openings to feed air to a central flame outlet.
A further form of burner includes a cover having a plurality of openings to expose a wick positioned below the cover. The openings are spaced apart a distance to define distinct burn areas. Examples of this type of device are disclosed in Swiss Pat. No. 57497 and German Pat. Publication No. 2 648 601.
Another form of burner device is disclosed in French Pat. No. 578565. This device includes an adjustable wick contained in a cage-like structure. In the raised position, the sides of the wick and the top surface are exposed to support combustion of the fuel.
Various other cooking fuel containers and burners have been disclosed in the prior art which are designed to produce efficient burning of the fuel. One such cooking fuel container and burner is described in U.S. Pat. No. 4,604,053. This food warming cartridge consists of a cylindrical container with a top cover closing the opening of the container. In a central portion of this container and top cover there is a square or rectangular region to expose a flat wick, the two ends of which extend downward into the fuel which is contained in the food warming cartridge. The fuel is fed up the wick to the burning surface where it is burned to provide the desired heat. This design does not provide for insulating the fuel containing region of the cartridge from the heat that is produced from the burning of the fuel. Thus, some of the heat from the burning fuel will be transmitted through the cover to the fuel. The heat produces pressure within the container forcing the fuel up the wick resulting in an uneven burn temperature and an inconsistent burn time.
U.S. Pat. No. 4,611,986 discloses a disposable liquid fuel burner. This liquid fuel burner is illustrative of a typical center wick burner where the wick extends downwardly through the top cover of a cylindrical fuel container. This wick extends a distance above the top cover to define a burn surface elevated a distance above the top cover above the burner. Since this device comprises a single central wick, it tends to produce a small diameter flame and thus a localized heating. It is preferred that the fuel burn surface be as large an area as possible to provide for a more even heating of buffet trays and chafing dishes. Also, typically fuel burners of this type do not have a substantially constant burn temperature throughout the full burn time.
U.S. Pat. No. 4,850,858 discloses a liquid fuel burner which provides an enlarged burn surface area. This liquid fuel burner consists of a cylindrical container which has a top closure. Within this top closure is an opening to provide for the enlarged burning surface. Within the container portion there is a wick which passes upwardly from the fuel region up into a wick region. This wick is of a single strand which passes upwardly through the center of a wick supporting table and overlays this wick supporting table. Overlaying the wick is a non-combustible fiber bat and a plastic foam bat as an ignitor. The plastic foam bat is ignited and burns away and in most instances will effectively light the fuel in the fiber bat which then provides the burning surface for the liquid fuel.
U.S. Pat. No. 4,896,653 discloses a cooking fuel can and burner having a central recessed area and peripheral air vents. A drawback of this type of a cooking fuel product is the lack of a constant heat profile. This type of cooking fuel container will produce a lower heat level upon ignition followed by an increasing level of heat production during the burning of the fuel and tapering to a lower burn temperature at the end of the burning period. In addition, this type of a center wick structure does not provide for the advantages of a burn surface which has an enlarged burn surface region.
U.S. Pat. No. 4,991,139 discloses a liquid fuel container which has a center wick extending upwardly from the top of the container. This liquid fuel container suffers from the same problems as other center wick burners by providing only a localized heating of the buffet server or chafing dish. Further, this type of a cooking fuel containers does not provide for the essentially constant flame temperature throughout the burning of the contained fuel.
There is accordingly a continuing need in the art for a fuel container that is able to maintain a high temperature for extended periods of time. There is further a need for a cooking container that is able to produce uniform heating at high temperatures while consuming the fuel in a clean and efficient manner. The previous fuel burning containers are not able to produce a high temperature without consuming large quantities of fuel.